# Handling Falsy types

Hooks in `useDapp` support handling "falsy" values in most parameters.

```tsx
export type Falsy = false | 0 | '' | null | undefined
```

If you pass one of these types to a call, it will return `undefined` without making blockchain query. This allows us to conditionally make a call if a parameter is not known ahead of time, without breaking the [Rules of Hooks](https://reactjs.org/docs/hooks-rules.html).

## Example

```tsx
const {account} = useEthers() // account is of type "string | undefined"
const balance = useEtherBalance(account) // Will start making queries once account is defined
```
